On a related note, the rail trails are nearly firm. We road the Badger State from Purcell down to a few miles past the tunnel on sunday, the first half mile is pretty awful (which is typical for that section) then it firms up and there is only the occasional puddle. We were on fat bikes which probably helped in some of the softer areas but I don't think a regular mountain bike tire would leave much more of an impression, a cross tire would probably leave a noticeable groove still.
We only saw one other bike the entire time and it happend to be Greg on the tractor, he turned around and rode back with us so we had a nice little phlock of fatties marching down the trail. Greg's tractor has to be one of the nicest bikes in the area.
Oh, and be very careful in the tunnel, there are basketball sized stalagmites of ice all over the floor on the north end that are perfectly designed for knocking over cyclists, especially those that forget to bring a light.